Begin at least 4 hours before serving.
Preheat the oven to 160ºC/320ºF/Gas 2.  Place the steak and kidney in a plastic bag with the salt, pepper and flour. Close the bag and shake well until the meat is thoroughly coated.

Heat 2 to 3 tbsp oil in casserole dish over a high heat; sear the meat all over in the hot oil in 2-3 batches, adding more oil each time. Remove with a slotted spoon and leave set aside.
Add the onions and mushrooms to the casserole and cook for 2-3 Minutes. Add the tomato puree and cook for a further 2-3 minutes. Deglaze with the Guinness, add bay leaves, thyme, steak and kidney and stock. Bring to the boil then cover and place in the oven for 1½ hours.
Take the casserole out of oven and place on the hob. Reduce the sauce over a medium heat to a smooth consistency and allow to cool.

To complete the cooking, preheat the oven to 180ºC/360ºF/Gas 4.
Place the steak and kidney from the casserole into a 1 litre pie dish and brush the pie rim with egg yolk. Roll out the pastry to 5 mm thick and place on top of the pie dish, carefully pressing down the rim. Brush the pastry with the remaining egg yolk and bake in the middle of the oven for 35-40 minutes. Serve immediately.

Serve with creamy mashed potatoes, garden peas and carrots